Mange in Dogs: Sarcoptic vs Demodectic — Causes & Treatment

Mange is one of the most distressing skin conditions a dog can develop. Intense itching, hair loss, thickened skin, and secondary infections can make an affected dog miserable — and, in some cases, pose a risk to human household members as well. There are two fundamentally different types of mange in dogs, caused by two entirely different species of mite, and they require distinct approaches to treatment. Understanding the differences is essential for fast, effective care.

Sarcoptic Mange (Scabies) — Caused by Sarcoptes scabiei

Sarcoptic mange, commonly known as canine scabies, is caused by Sarcoptes scabiei var. canis, a microscopic mite that burrows into the superficial layers of the skin. Female mites tunnel through the epidermis to lay their eggs, and this burrowing activity triggers an intense inflammatory and immune response that causes severe, relentless itching. The Guide">Guide">Guide">mites complete their entire life cycle — from egg to adult — on the host in approximately 17–21 days.

How it spreads: Sarcoptic mange is highly contagious. It spreads rapidly through direct contact between dogs — at dog parks, in kennels, through wildlife contact (foxes are a significant reservoir in the UK and Europe), or even via contaminated bedding, grooming tools, or furniture where mites can survive off-host for several days. All dogs in the same household should be treated simultaneously, regardless of whether they show symptoms.

Zoonotic risk: Sarcoptes scabiei can temporarily infest humans, causing itchy red papules and tracks, particularly on the arms, torso, and waistline. The human variant of scabies (S. scabiei var. hominis) is a separate strain, but canine mites can cause significant symptoms in people before they naturally die off (they cannot complete their life cycle on humans). Any family members developing unexplained itchy rashes while the dog is being treated should consult a physician.

Symptoms of Sarcoptic Mange

The hallmark of sarcoptic mange is extreme pruritus (itching) that is often disproportionate to the visible skin changes — especially early in the infection. The most affected areas initially are those with sparse hair cover: the ear margins, elbows, hocks, ventral abdomen, and chest. As the condition progresses, the following signs develop:

• Intense, relentless scratching and biting at the skin
• Hair loss (alopecia) in affected areas, often symmetrical
• Red, inflamed, crusted skin with yellow or grey scaling
• Thickened, wrinkled skin (lichenification) in chronic cases
• Ear margin crusting — a classic early sign of sarcoptic mange
• Positive pinnal-pedal reflex: scratching the ear margin causes the dog to scratch reflexively with the hind leg — a useful clinical indicator
• Secondary bacterial skin infections (pyoderma) from self-trauma
• Weight loss and lethargy in severe or prolonged cases

Demodectic Mange — Caused by Demodex canis

Demodectic mange is caused by Demodex canis, a cigar-shaped mite that lives in the hair follicles and sebaceous glands of dogs. Unlike Sarcoptes, Demodex is a normal inhabitant of healthy dog skin, transmitted from mother to puppy during the first few days of life through close nursing contact. In dogs with healthy immune systems, the mite population is kept in check with no ill effects. Disease only occurs when the immune system fails to regulate mite numbers adequately, allowing the population to explode.

Not contagious: Demodectic mange is not contagious between dogs or to humans. A dog developing demodicosis is not a risk to other pets or household members. The condition reflects immune dysregulation in the affected individual, not external transmission.

Who gets it: Demodectic mange most commonly affects young dogs between 3 and 18 months old, before their immune systems are fully mature. In older dogs, generalised demodicosis often signals an underlying systemic disease suppressing immunity — hypothyroidism, Cushing's disease, cancer, or long-term corticosteroid use. Certain breeds, including Bulldogs, Shar-Peis, Pit Bull Terriers, and Dachshunds, have a hereditary predisposition.

Symptoms of Demodectic Mange

Demodectic mange presents in two forms: localised and generalised. The distinction matters enormously for prognosis and treatment decisions.

Localised demodicosis consists of one to five small, well-defined patches of hair loss, typically on the face (around the eyes and muzzle) or forelegs. These patches may appear scaly or slightly reddened but rarely itch significantly. In young dogs, up to 90% of localised cases resolve spontaneously as the immune system matures, without any treatment. Monitoring under veterinary supervision is usually appropriate.

Generalised demodicosis involves widespread hair loss affecting large areas of the body or more than five lesion sites. The skin becomes thickened, hyperpigmented, and greasy, with a characteristic musty odour. Secondary bacterial folliculitis and furunculosis (ruptured infected follicles) are common complications that cause significant discomfort, swelling, discharge, and pain. Generalised demodicosis in adult dogs requires a thorough investigation for underlying disease.

Diagnosis — Skin Scraping and Beyond

The primary diagnostic test for both types of mange is the deep skin scraping, in which the vet uses a scalpel blade to scrape skin cells from multiple affected areas until capillary bleeding is seen (indicating sufficient depth). The material is examined under a microscope for mites, eggs, or faecal pellets.

For demodectic mange, skin scrapings are highly reliable — Demodex mites are found in abundance in active disease. For sarcoptic mange, however, mites are notoriously difficult to find due to their low numbers and deep burrowing; a negative scraping does not rule out the diagnosis. In suspected sarcoptic cases with negative scrapings, many vets will conduct a therapeutic trial — treating for scabies empirically and assessing the response. Resolution of intense pruritus within 2–4 weeks of treatment strongly supports the diagnosis. Serological (blood) tests for Sarcoptes antibodies are available in some referral settings but are not widely used in general practice.

When generalised demodicosis is diagnosed in an adult dog, the vet will typically recommend blood tests, urinalysis, and potentially imaging to screen for underlying conditions driving immune suppression.

Treatment Options for Sarcoptic Mange

Sarcoptic mange responds well to several veterinary treatments. The choice depends on the dog's size, age, breed, and any contraindications.

Isoxazolines — including fluralaner (Bravecto), sarolaner (Simparica), and afoxolaner (NexGard) — are now first-line treatments for sarcoptic mange in many countries. These oral prescription medications work by blocking chloride channels in the mite's nervous system, causing rapid death. They are highly effective, easy to administer, and have the advantage of also providing broad-spectrum flea and tick control. A single dose of Bravecto provides 12 weeks of coverage; monthly oral isoxazolines are also effective. Clinical improvement is typically dramatic within 2–4 weeks.

Selamectin (Revolution), a topical spot-on applied monthly, is another well-established and effective option, particularly useful for dogs that cannot take oral medications. It acts on the mite's nervous system through a different mechanism (avermectin class) and has a good safety profile across most breeds.

Ivermectin, administered orally or by injection, was historically the standard treatment and remains effective. However, it carries significant risks in certain breeds — most notably Collies, Shetland Sheepdogs, Australian Shepherds, and related breeds that carry the MDR1 (ABCB1) gene mutation, which impairs drug efflux from the brain. In these breeds, ivermectin can cause severe neurotoxicity and is contraindicated unless genetic testing confirms the dog does not carry the mutation. For this reason, isoxazolines and selamectin are generally preferred today.

All in-contact dogs must be treated simultaneously, and the environment (bedding, soft furnishings) should be thoroughly cleaned or replaced. A follow-up scraping or clinical assessment 4–6 weeks after treatment completion is advisable.

Treatment Options for Demodectic Mange

Localised demodicosis in young dogs is typically managed with watchful waiting. The vet may recommend a topical antiparasitic gel or lotion for isolated lesions, along with supportive care for skin health. Steroids and immunosuppressive drugs should be avoided entirely in demodectic mange, as they worsen the immune dysregulation driving the disease.

Generalised demodicosis requires systemic treatment. Isoxazolines (Bravecto, Simparica) are now the treatment of choice for generalised demodicosis due to their excellent efficacy, ease of administration, and safety profile. Treatment is typically continued monthly until two consecutive negative skin scrapings are obtained at least one month apart. This may take 3–6 months or longer in severe cases.

Historically, amitraz — a topical dip — was the standard treatment and remains effective, but it requires careful handling due to toxicity to the handler, other pets, and children, and requires sedation or very careful application. It is less commonly used now that oral isoxazolines are available.

Any underlying disease identified during workup must be addressed concurrently. Successful treatment of the root cause of immune suppression (e.g., managing Cushing's disease or discontinuing unnecessary steroids) is often as important as the antiparasitic treatment itself.

Managing Secondary Skin Infections

Secondary bacterial infections are extremely common in both types of mange and must be treated alongside the antiparasitic therapy. Your vet will prescribe systemic antibiotics (commonly cefalexin, amoxicillin-clavulanate, or doxycycline) based on the severity of infection. Medicated shampoos containing chlorhexidine or benzoyl peroxide can help reduce bacterial load on the skin surface, remove crusts, and improve comfort during treatment. These are valuable adjuncts to prescription treatment.

Prognosis

With prompt, appropriate treatment, the prognosis for sarcoptic mange is excellent. Most dogs recover fully within 4–8 weeks. Reinfection from untreated contact animals or environmental sources remains the most common cause of treatment failure, making simultaneous treatment of all pets and environmental decontamination essential.

For localised demodicosis in young dogs, the prognosis is very good, with the majority resolving without active treatment. Generalised demodicosis carries a more guarded prognosis, particularly in adult dogs with underlying disease. In young dogs without a predisposing illness, around 90% of generalised cases ultimately resolve with appropriate treatment, though it may take six months to a year. In adult dogs, long-term management is sometimes required, particularly if the underlying immunosuppressive condition cannot be fully resolved.

Written by Sarah Bennett, Certified Animal Nutritionist. This article is for informational purposes only and does not constitute veterinary advice. Always consult a licensed veterinarian for diagnosis and treatment of your pet.